Connecting conduit for a cryogenic fluid

Abstract

A connecting line (1) for a cryofluid with a flexible tube (5) which is provided at each end (7, 8) with a connection fitting (2, 3) is characterized in that the tube (5) lies with circumferential clearance in a rigid tube (6), the ends (9, 10) of which are tightly connected to a connection fitting (2, 3) each, so that the clearance (7) between tube (5) and tube (6) can be evacuated, wherein at least one of the tight connections between tube end (9, 10) and connection fitting (2, 3) is made via a bellows cuff (13, 14), in the extended position of which the tube (5) is less curved and in the contracted position of which the tube (5) is more curved.

Description

[0001] The present invention relates to a connecting line for a cryofluid, comprising a flexible hose which is provided with a connection fitting at each end.

[0002] US 3,068,026 and US 2023 / 0139421 A1 disclose connecting lines for cryofluids.

[0003] Cryogenic fluids such as liquefied hydrogen or liquefied natural gas (LNG) are frequently used as high-energy-density fuels for vehicles, e.g., trucks or buses. These cryogenic fluids are stored in cryogenic tanks, which are mounted, for example, on both sides of the vehicle's chassis. To easily fill such dual tanks from one side of the vehicle, connecting lines between the tanks and their filling and emptying valves are required.

[0004] To maintain the extremely low temperatures of cryogenic fluids, e.g., approximately -252 °C in the case of liquid hydrogen or approximately -161 °C in the case of LNG, the connecting lines between components must be exceptionally well insulated. Double-walled constructions with vacuum insulation are typically used for this purpose. However, the application of such constructions to a vehicle chassis presents an additional challenge, as the connecting lines must be able to withstand vibrations and torsional forces of the vehicle chassis, which can cause significant changes in the relative positions of the connected components.

[0005] The invention aims to create a connecting line for cryofluids that meets these requirements.

[0006] This objective is achieved with a connecting line for a cryofluid, with a flexible tube that is provided with a connection fitting at each end, wherein the tube lies with circumferential play in a rigid tube, the ends of which are each tightly connected to one of the connection fittings, so that the space between the tube and the tube can be evacuated, wherein at least one of the tight connections between the tube end and the connection fitting is made via a bellows cuff, in the extended position of which the tube is less curved and in the contracted position of which the tube is more curved.

[0007] The connecting line of the invention creates a vacuum-insulated double-wall structure which can follow any relative movements of the connected components and thus also strong vibrations and twisting of a vehicle without damage. This ensures extensive or even complete vacuum thermal insulation of the cryofluid at all times.

[0008] Preferably, not just one, but each of the two tight connections between the respective pipe end and the respective connection fitting is made via a bellows sleeve. This allows the connecting line to individually accommodate the relative movements of the connected components at both ends and, for example, to be additionally fixed to the vehicle chassis in the middle.

[0009] It is particularly advantageous if at least one of the bellows cuffs is made of metal, preferably stainless steel. This gives the bellows cuff a springy resting position from which it can be extended and contracted, while simultaneously ensuring high gas tightness and elongation at break.

[0010] In a preferred embodiment of the invention, the hose is provided with an abrasion-resistant sheath, preferably made of fiberglass. This prevents wear of the hose due to abrasion during any contact with the inner wall of the pipe when the hose bends during the contraction or "springing" of the bellows cuff. A fiberglass sheath is particularly resistant to very low temperatures.

[0011] It is particularly advantageous to place a layer of thermally insulating material between the hose and the outer casing, especially a layer of multi-layered (heat-radiation insulating) aluminum foil with a heat-conducting insulating fleece between the layers. These measures improve the thermal insulation of the connecting cable.

[0012] According to a further preferred feature of the invention, a binding agent for hydrogen gas and / or residual gas can be arranged in the pipe. In particular, the binding agent can be contained in a grid cage with gas inlets, which runs alongside the hose in the pipe. Any residual gas and / or gas diffusing out through the hose, which over time could impair the vacuum in the space between the hose and the pipe and thus the thermal insulation, and lead to corrosion of the pipe, is thereby bound.

[0013] Advantageously, the pipe is made of metal, preferably aluminum, which gives the connecting pipe high strength at a low weight.

[0014] In all these embodiments, the tube can preferably be equipped on its outer side with an anchor for mounting to a vehicle chassis. This allows the relative movements occurring between the connected components to be divided into a first relative movement between one component and the tube, and a second relative movement between the tube and the other component.

[0015] In a further advantageous embodiment of the invention, each connection fitting comprises an inner fitting and an outer fitting surrounding it at a distance, wherein the inner fitting is connected to the hose end and the outer fitting to the pipe end or its bellows cuff, if present, and wherein the inner and outer fittings are tightly connected to each other via an annular structure recessed from their free ends. The free end of the inner fitting can be used for the cryofluid connection of the respective component, and the free end of the outer fitting creates a surrounding annular space relative to the inner fitting, which can, for example, be insulated with foam or reused for vacuum insulation. Furthermore, the outer fitting can bear the main load of the mechanical connection to the connected component, thus relieving the inner fitting, which serves for the cryofluid connection.

[0016] Furthermore, it is particularly advantageous for the ring structure to include a bellows section for load decoupling between the inner and outer spigots. The bellows section can also compensate for movements or misalignments between the inner and outer spigots that may occur when connecting the respective spigot to the respective component.

[0017] The invention is explained in more detail below with reference to an embodiment illustrated in the accompanying drawings. The drawings show Fig. 1 the connecting line of the invention in a perspective longitudinal section; and Fig. 2 one of the connecting pieces of the connecting line from Fig. 1 enlarged in detail in a perspective longitudinal section.

[0018] Fig. 1 Figure 1 shows a connecting line for a cryofluid. The cryofluid could be, for example, hydrogen, which is at least partially liquefied at temperatures of approximately -250 °C and pressures of up to 16 bar – or more, depending on the container design – or a comparable cryofluid suitable for use in internal combustion engines or fuel cells, such as liquefied natural gas (LNG) at a temperature of approximately -161 °C. The cryofluid could also be a refrigerant, such as liquid nitrogen, used to operate the cooling system of refrigerated trucks, for example, food transport vehicles.

[0019] The connecting line 1 has a connection fitting 2, 3 at each of its two ends, allowing it to be connected to a component, such as a fuel tank, a refrigerant tank, or a fitting for filling or emptying cryogenic fluid. For example, the connecting line 1 serves to connect two hydrogen tanks mounted on opposite sides of a truck, enabling them to be filled or emptied together from one side of the vehicle.

[0020] The connecting cable 1 is supported by the components connected via the connection fittings 2 and 3. Alternatively or additionally, it has an anchor point 4 on its outer side, by which it can be attached, for example, to a vehicle chassis. The connecting cable 1 is thus fixed to the vehicle chassis either at two anchor points, namely the connected components mounted on the vehicle chassis, or at three anchor points, namely the two connected components and the anchor point 4.

[0021] The connecting line 1 is an evacuable double-walled construction consisting of an inner cryogenic conduit in the form of a flexible hose 5 and a rigid pipe 6 surrounding it with circumferential clearance. The ends 7, 8 of the hose 5 are tightly connected to the ends 9, 10 of the pipe 6 via one of the connecting nozzles 2, 3 each. This allows the clearance or space 11 between the hose 5 and the pipe 6 to be evacuated for thermal insulation of the hose 5, e.g., via a closable evacuation opening 12 in the pipe 6.

[0022] At least one of the tight connections between the respective pipe ends 9, 10 and the respective connection fittings 2, 3 (here both tight connections) is made via a bellows sleeve 13, 14. The end 15 of the bellows sleeve 13 facing away from connection fitting 2 is connected to pipe end 9, and the end 16 of the bellows sleeve 14 facing away from connection fitting 3 is connected to pipe end 10. If only one bellows sleeve is used, e.g., between connection fitting 2 and pipe end 9, the other pipe end 10 can be directly and tightly connected to the other connection fitting 3.

[0023] The tube 6 and the bellows sleeves 13, 14 can be made of plastic, for example. For extremely low-temperature resistance, they are made of metal, such as stainless steel or aluminum. The bellows sleeves 13, 14 thus have a spring-like resting position between their extended and contracted positions.

[0024] The lengths of hose 5, pipe 6, and bellows cuffs 13, 14 are dimensioned such that, in a more widely separated position of one or both bellows cuffs 13, 14, hose 5 is less curved (e.g., straightened), and in a contracted position of one or both bellows cuffs 13, 14, hose 5 is more strongly curved. For example, Fig. 1 The resting position of the bellows cuffs 13, 14, in which the hose 5 runs through the tube 6 in a multiple bend. When one or both bellows cuffs 13, 14 are pulled apart, the hose 5 can straighten, and when one or both bellows cuffs 13, 14 are pulled together, it can bend more sharply.

[0025] This allows relative movements between the components connected by the connecting line 1 to be accommodated. If the anchorage 4 is used as the third anchorage point, one bellows cuff 13 and the curved hose 5 can compensate for relative movements between the anchorage 4 and one component, and the other bellows cuff 14 and the curved hose 5 can compensate for relative movements between the anchorage 4 and the other component.

[0026] The hose 5 is made of a flexible material, such as plastic or flexible metal. As abrasion protection against the inside of the pipe 6 in case of excessive bending of the hose 5, the hose 5 is optionally provided with an abrasion-resistant sheath 17. The sheath 17 can be made, for example, of a woven, non-woven, knitted, or fleece fiberglass material. Optionally, a layer 18 of a thermally insulating material is placed between the hose 5 and the sheath 17. For example, the layer 18 consists of a heat-radiation insulating aluminum foil, which is wrapped around the hose 5 in several layers, with a heat-conducting insulating fleece wrapped between the layers.

[0027] The construction of one of the connection nozzles 2, 3 will now be described using the following: Fig. 2 The details for connection port 2 are explained below. The design of connection port 3 is analogous.

[0028] According to Fig. 2 The connection fitting 2 comprises an inner fitting 19 that can be connected to the hose end 7, and an outer fitting 20 that can be connected directly or via the bellows section 13, if present, to the pipe end 9. The inner and outer fittings 19 and 20 are connected to each other via a ring structure 21. The ring structure 21 can create a tight connection between the inner fitting 19 and the outer fitting 20, allowing the space 11 to be thermally insulated separately and, in particular, evacuated. Alternatively, the ring structure 21 can be gas-permeable, so that the space 11 is pressurized and, if desired, evacuated together with the annular space 22 between the inner fitting 19 and the outer fitting 20.

[0029] The ring structure 21 is set back from the free ends 23, 24 of the inner and outer nozzles 19, 20 towards the pipe 6, so that the ends 23, 24 are freely accessible for the components to be connected, e.g., a vehicle tank or a fitting. For this purpose, the free ends 23, 24 of the inner and outer nozzles 19, 20 each have, for example, an end flange 25, 26 with a union nut 27, 28. This allows the inner nozzle 19 to be connected, for example, to a cryogenic fluid connection and the outer flange 20, for example, to a load-bearing thread that has an evacuation opening for evacuating the annular space 22.

[0030] To facilitate the creation of these connections, particularly the screw connections using the union nuts 27, 28, the ring structure 21 can optionally be connected to the outer nozzle 20 via an axially movable coupling 29. The coupling 29 allows the outer nozzle 20 to move inwards and outwards relative to the ring structure 21 and the associated inner nozzle 19, e.g., to retract the outer nozzle 20 to expose the end 23 of the inner nozzle 19 in order to screw the inner nozzle 19 to a cryofluid connection using the union nut 27. The outer nozzle 20 is then advanced again to fix it to the component to be connected using the union nut 28.

[0031] The coupling 29 includes a stop that limits the outward movement of the outer nozzle 20. For this purpose, one of the parts outer nozzle 20 and ring structure 21 (here: the ring structure 21) has an inner shoulder 30 and the other of the parts outer nozzle 20 and ring structure 21 (here: the outer nozzle 20) has an outer shoulder 31 that abuts it during the outward movement of the outer nozzle 20.

[0032] The coupling 29 can be rotatable or rotationally fixed. In a rotationally fixed coupling 29, the rotational position of the locking mechanism can be adjusted. For adjustment purposes, for example, the outer sleeve 20 can have an external toothed ring 32 and the ring structure 21 an internal toothed ring 33 (or vice versa), which toothed rings can engage with each other and thus achieve the rotational locking of the coupling 22. By moving the outer sleeve 20 inwards, the toothed rings 32 and 33 can be disengaged, and then the outer sleeve 20 can be rotated relative to the ring structure 21 to select a different rotational locking position, in which the outer sleeve 20 locks into place again when moved outwards. The ring structure 21 can have an annular recess 34 into which the outer sleeve 20 can enter during its inwards movement.

[0033] As in Fig. 2As shown, the ring structure 21 can optionally have a bellows section 35 to compensate for relative movements between the inner nozzle 19 and the outer nozzle 20, in particular tilting or offsets between their longitudinal axes. This can be useful to compensate for tolerances between a cryofluid connection to which the inner nozzle 19 is connected and an evacuation and load connection to which the outer nozzle 20 is connected, or to compensate for any bending movements of the inner nozzle 19 with the hose 5 when it moves.

[0034] The bellows section 35 integrated into the ring structure 21 can, for example, have an envelope that is approximately cylindrical and runs coaxially and with radial distances to both the inner nozzle 19 and the outer nozzle 20.

[0035] In the example shown, the ring-shaped recess 34 of the ring structure 21 lies between the bellows section 35 and the coupling 29. However, the bellows section 35 could be located elsewhere in the ring structure 21, e.g. in the form of a zigzag folded ring disc.

[0036] A binding agent 36 for hydrogen gas can be arranged in the pipe 6, particularly along the hose 5. The binding agent 36 can, for example, be contained in a grid cage 37 provided with gas inlets, which runs alongside the hose 5 in the pipe 6 along its entire length, approximately in a rod or bolt shape.

[0037] The invention is not limited to the embodiments shown, but includes all variants, modifications and combinations thereof that fall within the scope of the attached claims.

Claims

1. A connecting line for a cryogenic fluid, having a flexible hose (5) which is provided at each end with a connecting piece (2, 3), wherein the hose (5) is positioned with circumferential clearance in a rigid pipe (6), the ends (9, 10) of which are connected in a sealed manner to one of the connecting pieces (2, 3) respectively, such that the clearance space (11) between hose (5) and pipe (6) can be evacuated, characterised in that at least one of the sealed connections between pipe end (9, 10) and connecting piece (2, 3) is made via a bellows sleeve (13, 14), in the extended position of which the hose (5) is less curved and in the contracted position of which the hose (5) is more curved.

2. The connecting line according to claim 1, characterised in that each of the two sealed connections is made via a respective bellows sleeve (13, 14).

3. The connecting line according to claim 1 or 2, characterised in that the at least one bellows sleeve (13, 14) is made of metal, preferably from stainless steel.

4. The connecting line according to any one of claims 1 to 3, characterised in that the hose (5) is provided with a wear-resistant sheath (17), preferably made of glass fibre.

5. The connecting line according to claim 4, characterised in that a layer (18) made of thermally insulating material is interposed between hose (5) and sheath (17).

6. The connecting line according to claim 5, characterised in that the layer (18) is formed from a multilayer aluminium foil with a thermally insulating fleece between the layers.

7. The connecting line according to any one of claims 1 to 6, characterised in that a binder material (36) for hydrogen gas is arranged in the pipe (6).

8. The connecting line according to claim 7, characterised in that the binder material (36) is contained in a lattice cage (37) which is provided with gas inlets and runs next to the hose (5) in the pipe (6).

9. The connecting line according to any one of claims 1 to 8, characterised in that the pipe (6) is made of metal, preferably of aluminium.

10. The connecting line according to any one of claims 1 to 9, characterised in that the pipe (6) is equipped on its outer side with an anchorage (4) for mounting on a vehicle chassis.

11. The connecting line according to any one of claims 1 to 10, characterised in that each connecting piece (2, 3) comprises an inner connecting piece (19) and an outer connecting piece (20) surrounding the inner connecting piece with spacing, wherein the inner connecting piece (19) is connected to the hose end (7, 8) and the outer connecting piece (20) is connected to the pipe end (9, 10) or its bellows sleeve (13, 14), if present, and wherein the inner and outer connecting pieces (19, 20) are connected to one another in a sealed manner via an annular structure (22) backwardly offset in relation to their free ends (23, 24).

12. The connecting line according to claim 11, characterised in that the annular structure (22) contains a bellows section (35).

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